1. Technical Field
The following description relates to a display device, and more particularly, to a display device with a touch screen and a method of driving the same.
2. Discussion of the Related Art
Various input devices are being applied to various electronic systems including computers (for example, laptop computers, tablet computers, and personal digital computers) and communication equipment (for example, portable terminals and handheld communication equipment).
In various input devices, a capacitive touch screen is an input device that detects the position of a near object such as a finger, senses capacitive change that is caused by the near object, and thus determines a touched position.
A digitizer or a tablet personal computer (PC) is an input device that determines a position touched by a position indicator which is realized as a drawing device such as a stylus or a pen-shaped object, e.g. a pen.
Generally, digitizers have excellent position detection accuracy and resolution as compared to general touch sensors, but have a drawback in that the digitizers require an input-dedicated position indicator (e.g., a stylus or a pen). Therefore, it is required to combine an attribute (for example, convenience) of a touch sensor with the improved accuracy and resolution of the digitizer.
Hereinafter, a related art display device that enables the use of a finger and a pen will be described with reference to FIG. 1.
FIG. 1 is a sectional view illustrating a panel part (P) of a related art display device with a touch screen.
As illustrated in FIG. 1, the panel part (P) of the related art display device with a touch screen includes a cover 10, a capacitive touch panel 20, a liquid crystal panel 30, and an electromagnetic touch panel 40.
Here, the cover 10 is a surface that a touching object touches, and may act as a window of the display device through reinforcement processing. Also, the cover 10 may be formed of glass.
The capacitive touch panel 20 measures capacitive change before and after a touch to determine whether there is a touch and the coordinates of a touched region, and includes a plurality of driving electrodes and a plurality of sensing electrodes for sensing touch when a touch is inputted.
The liquid crystal panel 30 includes a liquid crystal layer formed between two glass substrates. The capacitive touch panel 20 is disposed on the liquid crystal panel 30, and the electromagnetic touch panel 40 is disposed under the liquid crystal panel 30.
An induced current, which is generated with a drawing device such as a stylus or a pen, flows in the electromagnetic touch panel 40, and thus, the electromagnetic touch panel 40 determines whether there is a touch and the coordinates of a touched region. The electromagnetic touch panel 40 includes a plurality of sensing electrodes forming a closed loop and a plurality of driving electrodes forming a closed loop, for generating an electromagnetic field for touch sensing.
However, a related art touch screen that enables capacitive touch sensing and electromagnetic touch sensing has a structure in which the capacitive touch panel 20 is disposed on the liquid crystal panel 30, and the electromagnetic touch panel 40 is disposed under the liquid crystal panel 30. For this reason, in the related art touch screen, the thickness of a product and manufacturing cost increase, and production yield decreases.
Moreover, during touch sensing in the capacitive type, when sensing touch in an electromagnetic type, noise due to a drawing device such as a stylus or a pen is inputted to the capacitive touch panel, and thus, a malfunction occurs in capacitive touch sensing.
Moreover, a driver for driving the capacitive touch panel 20 and a driver for driving the electromagnetic touch panel 40 may be driven at the same time, and thus, power consumption increases.